"""Capture from an active writer and compare a restored instance with its generation."""
from concurrent.futures import ThreadPoolExecutor
from pathlib import Path
import sys
from tempfile import TemporaryDirectory
import threading

from service_fixture import cli, serving, RatDBError

exe = Path(sys.argv[1]).resolve()
with TemporaryDirectory() as tmp:
    folder = Path(tmp)
    source = folder / "live.ratdb"
    restored = folder / "restored.ratdb"
    cli(exe, "init", source)
    with serving(exe, source, "--backup-dir", folder) as connect, connect() as reader:
        reader.select_warren("app")
        reader._request("create", kind="den", name="empty")
        reader.select_den("entries")
        reader.put("seq", {"n": 0})
        base = reader._request("stats")["generation"]
        first = threading.Event()

        def write():
            with connect() as writer:
                writer.select_warren("app")
                writer.select_den("entries")
                for n in range(1, 65):
                    writer.put("seq", {"n": n})
                    first.set()

        with ThreadPoolExecutor(max_workers=1) as pool:
            future = pool.submit(write)
            assert first.wait(15)
            result = reader._request("online_backup")
            future.result(timeout=60)
        generation = result["generation"]
        assert base < generation <= base + 64
        assert reader.get("seq")["n"] == 64
        reader.put("seq", {"n": 65})
        reader._request("online_backup")
        try:
            reader._request("online_backup")
        except RatDBError as error:
            assert error.code == "operation_failed"
        else:
            raise AssertionError("existing backup was overwritten")
        assert not list(folder.glob(".ratdb-online-*"))
        archive = folder / f"generation-{generation}.ratdb"
        assert result["backup"] == archive.name
        cli(exe, "restore", archive, restored)
    with serving(exe, restored) as connect, connect() as db:
        db.select_warren("app")
        assert "empty" in db._request("dens")["names"]
        db.select_den("entries")
        assert db.get("seq")["n"] == generation - base
        assert db._request("stats")["generation"] == generation
        assert db._request("check")["valid"]
        try:
            db._request("online_backup")
        except RatDBError as error:
            assert "backup-dir" in str(error)
        else:
            raise AssertionError("unconfigured backup was enabled")
    print(f"Restored generation {generation}, writer pause {result['writer_pause_us']} us")